The present invention relates to a method for activating a drive system for control surfaces or working systems of an aircraft, in which the speed of a drive unit of the drive system is regulated. Furthermore, the present invention relates to a corresponding drive system for control surfaces or working systems of an aircraft with a drive unit with speed regulation and a control.
Aircraft control surfaces on the one hand serve as primary control of the position control of the aircraft and on the other hand as secondary control for the configuration of the wing for adaptation of the wing profile to the desired airspeed.
The primary flight control generally comprises the ailerons, side rudders, elevators, and the adjustable tail planes.
The secondary flight control comprises the landing flaps at the trailing edge of the wings, the leading-edge flaps and the brake flaps on the upper surface of the wings.
In modern giant airplanes, all these control surfaces are actuated with either electric or hydraulic energy, which usually is provided by a drive unit and is transmitted to the control surfaces via a transmission.
In addition, airplanes comprise further working systems, so-called Utility Systems, such as freight door drives or thrust reverser drives, which likewise are actuated via hydromechanical or electromechanical drives.
The drive systems usually include overload protections to avoid structural damages in the case of an overload, e.g. by running onto the limit stops, gust loads or by jamming of the mechanical drive elements.
It is known to limit the chamber pressure of the control cylinders in the hydraulic servo actuators of the primary flight control by means of pressure relief valves. Since the actuating force is proportional to the chamber pressure, the response of the pressure relief valve also limits the actuating force.
Another known method, in particular in electromechanical drives of the primary flight control, is to measure the actuating force by means of electric sensors, whose signal is evaluated in an electronic control unit. When a maximum specified load is exceeded, the drive is deactivated.
From US 2006/0113933 A1, a sensor-based method for load limitation for electromechanical actuators is known, in which an inadmissible case of load is detected by measuring the engine input torque.
Both DE 10308301 B3 and DE 2004055740 A1 describe sensor-based electronic devices for limiting overloads in high-lift systems.
In conventional drive systems of the adjustable tail planes, however, mechanical load limiters are frequently used. In the drive systems of the high-lift means, if these are systems with a central drive unit with transmission shafts for power transmission, there are likewise used mechanical load limiters. Such system is shown in FIG. 1. The same comprises a speed-controlled central drive unit 1, which drives the load stations of the wing flaps 8 via a transmission shaft system. The torques initially are transmitted from the drive unit 1 via a transmission shaft to a half-wing branch transmission 3, from which the drivetrains of the two wings are branched off. In each drivetrain, simple transmissions 8 for a change in direction or for gear ratio adaptation and branch transmissions 6 for the load stations of the wing flaps 7 are provided.
The protection against high load peaks in a case of jamming is realized by the installation of station torque limiters in the branch transmissions 6 of the load stations and by half-system torque limiters 4 in the shaft train. The half-system torque limiters 4 are disposed in the transmission between the half-wing branch transmission 3 for the two wing halves and the branch transmissions 6 of the load station of the wing flaps and respond from a maximum total load admissible for the wing train, so that the loads are limited in the region behind the half-system torque limiters 4. In this region, the transmission therefore can be configured as a low-load transmission 5, whereas the transmission from the drive unit up to the half-system torque limiters 4 must be configured as a high-load transmission 2, which increases both weight and costs.